Laboratory-Scale Bioremediation of Crude Oil Polluted Soil Using a Consortia of Rhizobacteria Obtained from Plants in Gokana-Ogoni, Rivers State

Background: The use of consortia of rhizobacterial flora in bioaugmentation of autochthonous flora cannot be over-emphasized.

Aim: This study sought to assess the potentials of rhizobacterial obtained from pre-exposed plants to crude oil pollution at Bodo creeks, Gokana-Ogoni, Nigeria.

Methods: In this 4-weeks study, polluted soil was spiked using a soil auger while three different plants were randomly obtained from the study area and aseptically transported to the environmental microbiology laboratory, University of Port Harcourt. Baseline physicochemical and microbiological evaluation was performed on the soil samples. Biochemical and morphological features were employed in the characterization of the isolates. Bioremediation monitoring was performed on spiked soil of total petroleum hydrocarbon concentration of 17,000 mg/kg within 14 days of the study. Percentage degradation of the crude oil was evaluated.

Results: The three plants, Schoenoplectus senegalensis, Fuirena umbellata and Cyperus tuberosus from whose rhizobacteria were randomly obtained at different points at a depth of 10-15 cm. pH in the untreated soil was observed to increase from 6.38-6.48 after 14 days exposure time. The electrical conductivity in the treated increased from 186.2-188 µs/cm. The Nitrates in the soil for the bacterial treatments alone fell from 3.42-2.51 mg/kg. Phosphates for the bacteria consortium decreased from 23.8-22.57 mg/kg. Hydrocarbon Utilizing Bacterial Count increased from 4.3 x 105 cfu/g at day 0 to 2.7 x 106 cfu/g at day 7 and 1.7 x 106 cfu/g at day 14. Total Heterotrophic Bacterial Count increased in the control from 2.0 x105 cfu/g at day 7 to 3 x 106 cfu/g at day 14. Bacterial isolates were Kingella sp, Bacillus sp and Pseudomonas sp., Corynebacterium sp, Klebsiella sp, Staphylococcus sp, and Bacterioides sp. Bacillus sp and Pseudomonas sp are most represented with 32% and 23% respectively. TPH concentration decreased from the baseline value to 13647 mg/kg in 7 days and further decreased to 9034 mg/kg at day 14. The PAHs concentration decreased from 2998.71 at day 0 to 1986.43 and 1352 mg/kg at day 14.

Conclusion: Biomining potential of rhizobacterial as observed in this study suggest a limitless application.